Online advertising uses the Internet to deliver marketing messages to Internet visitors. Online advertising business continuously grows with the development of network technologies and the popularization of the Internet. There are various aspects to online advertising, one of which is lead generation. With lead generation, a lead seller may advertise online, often through multiple channels, in order to drive visitor traffic to specific landing pages. Each landing page may enable an Internet visitor to provide some relevant information. Based on the information provided by the visitors, the lead seller may determine whether a visitor qualifies as a lead for some of its clients (the lead buyers), and if so, the lead seller may forward the visitor's information to the specific lead buyers. The visitor thus becomes a lead for these lead buyers.